Various forms of measuring devices have been in use for years with the two most common devices being the folding measure ruler commonly used by carpenters and the convenient hand-held tape measure.
One of the attributes of the hand-held tape measure is that it is lightweight and easily stored and used; the tape is compactly coiled within the housing and is spring-biased to retract into the housing when not in use. This device provides an additional feature in that the tape as it is extended has a slightly concave cross section which allows the tape to extend outwardly in a self-supporting configuration for a substantial distance.
The primary drawback with this type of device is that it requires that both hands of the operator be in use in order to extend the tape with one hand holding the housing and the other hand extending the tape from its coiled position within the housing.
The present invention is directed to a way of conveniently extending and retracting the tape from the housing by means of a power mechanism without manual effort.
A variety of power-operated measuring tapes have been disclosed with power mechanisms for extending or retracting the metal tape out of or into the housing without manual effort. One such disclosure involves two separate electric motors with one of the motors arranged to drive a sprocket wheel that has teeth drivingly engaged with evenly-spaced openings extending along the length of the tape. The second motor is connected directly to the spool on which the tape is wound and when energized, this spool is rotated to pull the tape back onto the spool.
There is also known an electronic measuring tape which uses a magnetic reader to read measurements along with a motor driven ratchet wheel mechanism to rewind the magnetic tape.